Process for quenching flames and extinguishing fires and devices therefor

ABSTRACT

A process for quenching flames which involves directing thereat symmetrical dibromotetrafluoroethane (BrF2C-CF2Br, 1,1,2,2tetrafluoro-1,2-dibromoethane) through a nozzle having a chamber traversed by this compound prior to emission from the orifice thereof which frustoconically converges in the direction of the orifice with half angle (conicity angle) of the cone ranging from 4* to about 20*, preferably between 5* and 18*. Preferably the outlet orifice at the exit of the chamber is elliptical with a ratio between the major half axis and the minor half axis between 5 and 1, preferably between 2.5 and 1.25, while the inlet orifice is circular and the transition from inlet orifice to outlet orifice is continuous. The dibromotetrafluoroethane is projected as a jet from this chamber at a pressure between 4 and 20 atm.

169-4-7. OR 396029312. SR

7 i I "M 3,602,312

[72] Inventors Nicolino Rainaldi 2,959,359 11/1960 Casaletto 239/601 XMestre; 3,343,794 9/1967 Voitsekhovsky 239/601 X Pierluigi Fatutto,Venezia. both of, Italy FOREIGN P [21] Appl. No. 841,460 9 l [22] FiledJuly 14 1969 589,990 1/1960 Canada OTHER REFERENCES {45] PatentedAug.31,l971 v Herzka and Pickthall PRESSURIZED PACKAGING [73} AssigneeMontecatiniEdisonS.p.A.

Milan, Italy (AEROSOLS). London, Butterworths Scientific Publica- [32]Priority July 15, 1968, Apr. 24, 1969 tions. 1958. Chapter 111. page 76.QD 549 H47. Copy in [33] Italy group 220. [3] l8982A/68 and MONA/69Primary Examiner-M. Henson Wood, Jr.

Assistant Examiner-Edwin D. Grant A!!0rneyl(arl F. Ross [54] PROCESS FORQUENCHING FLAMES AND EXTINGUISHING FIRES AND DEVICES ABSTRACT: A processfor quenchlng flames whlch involves THEREFOR I 17Claims6Drawing Figsdirecting thereat symmetrical dlbromotetrafluoroethane (BrF c-CF Br,1,1,2,2-tetrafluoro-1,2-dibromoethane) [52] U.S.Cl 169/1 through anozzle having a Chamber traversed by i [511 A62c pound prior to emissionfrom the orifice thereof which [50] Field of Search i 169M 1frustoconically converges in the direction of the orifice with lBing/601 half angle (conicity angle) of the cone ranging from 4 to about20, preferably between 5 and 18. Preferably the out- [561 Referencescied let orifice at the exit of the chamber is elliptical with a ratioUNITED STATES PATENTS between the major half axis and the minor halfaxis between 5 587,532 8/1897 Morgan 169/31 and 1, preferably between2.5 and 125, while the inlet orifice 1,768,700 7/1930 MacGregor 169/31is circular and the transition from inlet orifice to outlet orifice2,021,981 11/1935 Bichowsky 169/1 A is continuous. Thedibromotetrafluoroethane is projected as a 2,653,130 9/1953 Eiseman169/1 jet from this chamber at a pressure between 4 and 20 atm.

BrF C 0 E281 ATENTEU M1831 I97;

sum 1 or 2 INVIL'N'I'O/(S:

NICOLINO RAINALDI BY PIERLUIGI F UTTO ATTORNEY ATENTED AUBBI I971 SHEET2 OF 2 FIG.3

BrF C-CE Br INVENTORS:

NICOLINO RAINALDI y PIERLUIGI FATUTTO FIG.4

ATTORNEY PROCESS FOR QUENCI-IING FLAMES AND EXTINGUISHING FIRES ANDDEVICES THEREFOR SPECIFICATION Our present invention relates to a methodof quenching fires and extinguishing flames using as the extinguishingcompound dibromotetrafluoroethane and to a device for carrying out thismethod.

The highly efi'rcient flame-quenching and fire-extinguishing propertiesof symmetricaldibromotetrafluoroethane (BrF C- CF Br) have beendescribedin our copending application Ser. No. 827,959, filed May 26, 1969. Ithas been pointed out prior to our discoveries that various substanceshave greater capacity than others as flame-extinguishing materials andmay be used to advantage in fire extinguishing of the canister or tanktype. For the purposes of the present application, a fire extinguisherof the canister type will be one which has a self-contained pressuresource, e.g.- a liquid propellant, a pressurized gas propellant or thelike, from which the flame-extinguishing compound is driven in the formof a jet through a hose, pipe, tube or outlet orifice. Tank-typeextinguishers within the meaning of the present application, are thosewhich may be mounted on wheels or may constitute part of a vehiclestructure and may be provided with a self-contained pressure source, butalso may consist of a reservoir for the fire-extinguishing compound orcomposition which is driven through the outlet orifice, e.g. at the endof a hose more readily manipulatable by the user than an entire canisteror as part of a permanent installation, by a pump or other driving meansindependent of the reservoir.

As indicated earlier, sym-dibormotetrafluoroethane has been found tohave peculiarly advantageous properties as a flame extinguishingsubstance since it apparently is not readily dispelled from thecombustion site, absorbs surprisingly large quantities of heat and alsoform an oxygen-excluding blanket about the combustion site. For the mostpart, prior attention to fire-extinguishing compounds have concentratedupon finding substances with optimum characteristics, either as aheatdissipating or cooling agent at the site of combustion or as anoxygen-blocking noncombustible material capable of reducing theavailability of combustion-supporting air. Most surprisingly, bothproperties are combined in dibromotetrafluoroethane, which has even beenfound to have vastly superior flame-extinguishing properties bycomparison with its homologues and members of the halogenatedhydrocarbonfamily.

Further investigations have, however, shown that the use ofdibromotetrafluoroethane as a flame-quenching, fire-extinguishingsubstance has certain drawbacks and is less than fully satisfactory,because of the relatively large quantity of the material required toextinguish a fire and the time required for such extinction.

It is, therefore, the principal object of the present invention toprovide an improved method of extinguishing fires and quenching theflames of fires wherein the aforementioned disadvantages are obviated.

Another object of this invention is to provide an improvedmethod ofextinguishing fires with dibromotetrafluoroethane and thereby extendingthe principles set forth in our copending application Ser. No. 827,959,mentioned earlier.

It is further an object of this invention to provide a method ofextinguishing fire in a combustible liquid, characterized by its spreadover large surfaces, in an economical fashion, both with respect to thequantity of the extinguishing compound used per unit area of thecombustion site and with respect to the time required for totalquenching of the fire.

Another object of the instant invention is to provide an improved deviceor system for carrying out the method of the present invention and forextinguishing fires and quenching flames withsym-dibromotetrafluoroethane in much shorter times than has beenpossible heretofore and with a minimum quantity of this flame-quenchingagent.

Still another object of the present invention is to eliminate or reducethe above-described drawbacks, thereby obtaining a quenching of theflame'in short order, even on burning surfaces of considerable spreadand with a limited consumption of the fire-extinguishing product.

It is yet another object of our invention to provide a process forextinguishing fires which is applicable both to mobile fireextinguishingapparatus, such as portable fire extinguishers or wheel-mounted fireextinguishers, and to fixed fire-extinguishing equipment installed neartanks containing liquid combustibles or near machinery, in thefire-extinguishing installations of industrial, especially chemical,plants.

We have found, most surprisingly, that these objects and others whichwill become apparent hereinafter are attainable in a process forquenching flames and extinguishing fires which involves the step ofdirecting at a combustion site a jet, stream or spray of symmetricaldibromotetrafluoroethane (BrF C-CF Br) through a nozzle which,immediately behind the discharge orifice and through' which thedibromotetrafluoroethane is ejected, is formed with a frustoconicalchamber with a half angle a (conicity angle) of the corresponding coneranging between 4 and about 20 and preferably between 5 and 18, thechamber converging toward the outlet orifice. I

The present discovery is indeed surprising in view of the fact thatefforts in the art have heretofore concentrated upon the widespreaddissemination of the fire-extinguishing substance in such manner as toobtain the broadest possible spread of the discharge from the nozzlethrough which the composition is ejected. Hence, efforts along theselines have concentrated on the use of aerosol sprays, divergent nozzlesor nozzles having chambers diverging toward their mouth or dischargeorifice.

According to a further feature of the invention thedibromotetrafluoroethane is discharged, ejected or sprayed from a nozzlewhose discharge orifice, which has a cross-sectional area (flow acrosssection) less than the cross-sectional area or flow cross section of theinlet orifice of the frustoconical converging chamber, is of somewhatelliptical configuration with a ratio of the major half axis to theminor half axis of the ellipse ranging between 5 and 1 (5:1 to 1:1) andpreferably between 2.5 and 1.25 '(2.5:1 to 1.25:1). In this case, thesurface of the frustocone converges smoothly and continuously toward theelliptical orifice from the circular orifice and provides a continuousfrustoconical transition therebetween. Of course, the present inventionalso contemplates the use of chambers conforming to a frustum of a rightcircular cone.

Still another feature of this invention resides in the step ofdischarging the dibromotetrafluoroethane from the nozzle at a pressurebetween 4 and 20 atm., i.e. the driving pressure behind thedibromotetrafluoroethane is 4-20 atm. and preferably between 6 and 16atm. As previously noted, the driving force may derivefrompressurization of a reservoir containing thedibromotetrafluoroethane, e.g. a propellant having a high-vapor pressureand constituting a vapor at operating temperatures. The propellant maybe a pressurizing gas which may have flame-quenching properties itselfor may be inert with respect to the flame-quenching action, andpreferably is not combustion sustaining, or gases designed to drive thedibromotetrafluoroethane through the nozzle without mixing or miscibletherewith. Furthermore, propellants need not be used, but pumps or thelike may be employed to displace the dibromotetrafluoroethane at thedescribed pressure.

We have found that this method of extinguishing fires usingdibromotetrafluoroethane is highly suitable for the quenching of flamesrising from combustible liquids spread over relatively wide areas, e.g.flammable gasoline, oil, solvents and the like spread on water, ship anddock structures, areas surrounding tank farms, chemical plant equipment,etc. However, the extinguishing process may be used effectively alsomaterials as well.

Still another aspect of 'the invention resides in the apparatus ordevice for carrying out the aforementioned method and, therefore, themeans for combatting fires, extinguishing flames, etc. Withdibromotetrafluoroethane, according to this aspect of the invention, anozzle is provided ahead of a source of dibromotetrafluoroethane underpressure, the nozzle having a discharge orifice fed by a frustoconicalchamber converging in the direction orifice fed by a frustoconicalchamber converging in the direction of this orifice with a conicityangle a or half angle of the corresponding cone which lies between 4 and20 but preferably is between and 18. This chamber, which has thecircular inlet orifice mentioned earlier, may have a circular dischargeorifice or an elliptical discharge orifice, also as mentioned above. Thesection of the outlet orifice conforms preferably to the minor base ofthe frustocone.

The above and other objects, features and advantages of the presentinvention will become more readily apparent from the followingdescription, reference being made to the accompanying drawing in which:

FIG. 1 is an axial cross-sectional view, partly in diagrammatic form, ofa nozzle for use in the present method;

FIG. 2 is an end view taken in the direction of the discharge.

orifice of FIG. 1;

FIG. 3 is a view similar to FIG. 1 of another embodiment of a nozzleaccording to the present invention with the section being taken in theplane of the minor axis of the elliptical discharge orifice;

FIG. 4 is an end view of the nozzle seen in the direction of thedischarge orifice;

FIG. 5 is a cross-sectional view taken generally along the lines V+V ofFIG. 3; and

FIG. 6 is a somewhat diagrammatic view, in elevation, of an apparatususing the nozzle of FIGS. 1 and 2 or FIGS. 3-5.

In FIGS. 1 and 2 I show a nozzle N to which symdibromotetrailuoroethaneis fed as represented by arrow D for directing a jet of thedibromotetrafluoroethane onto the site of combustion as afire-extinguishing and flame-quenching composition.

This nozzle has a circular base 2 at one end of his body which may beaffixed to a nozzle of dibromotetrafluoroethane under pressure, e.g. bymeans of a threaded coupling, along the inner wall of'a cylinder bore 2'formed in this portion of the nozzle body.

The forward end of the nozzle body converges frustoconically in thedirection of discharge of the dibromotetrafluoroethane and is providedwith a chamber 3 axially extending within the body and terminating in adischarge orifice 4 of circular configuration at the front end of thenozzle body. The nozzle 4 is of smaller cross section than the inletorifice 5 of the chamber 3 at which the dibromotetrafluoroethane isadmitted into this chamber. The noule may be fitted onto a vessel,container or any conventional source of a pressurized liquid, such as acylinder or bottle containing dibromotetrafiuoroethane and a propellantas described in the aforementioned copending application and describedabove, The chamber 3 has a frustoconical configuration conforming to afrustum of a right circular cone with an apex angle in the longitudinalsection ABC between about 4 and about 20.

The flame-quenching, fire-extinguishing composition is ejected throughthe nozzle 1 in the direction represented by arrow D and flows from theorifice 4, the cross section of which coincides with the minor base ofthe frustocone 3 and with a truncating plane through the imaginary coneof apex angle 2a or conicity angle (half angle) a and the axis CE, witha generatrix AC.

As noted earlier, the shape of the orifice 4 may vary depending upon thespecific requirements. Thus the discharge orifice 4 may be of circularconfiguration (FIGS. 1 and 2) or, preferably, of ellipticalconfiguration (FIGS. 3-5) as shown for the orifice 4' of the nozzle N.Other configurations of discharge orifice have also been found to besatisfactory, although the elliptical shape has proved to be the mosteffechydrocarbons tive inasmuch as it permits coverage of wider areas bycomparison with circular discharge orifices for equal quantities ofproduct discharged. As a practical manner, the elliptical orifice hasbeen shown to be more efficient in disseminating the product emergingfrom the nozzle.

In the embodiment illustrated in FIGS. 3-5, the frustoconicaI chamber 3'has a minor base corresponding to the orifice 4' of ellipticalconfiguration while the major base 5 is represented by the inlet orificeto the chamber 3' is a continuous transition between the circular crosssection of the inlet orifice 5' to the elliptical configuration of thedischarge orifice 4' so that the immediate cross sections gradually andprogressively transform from the one geometrical shape to the other.

The conicity of such a chamber can be defined by two values of the halfangle a of the cone. Thus one may define a half angle a corresponding tohalf the apex angle of the cone in the plane ABC (FIG. 5) and an anglea" corresponding to the half angle of the cone in the plane ABCorthogonal to the plane ABC. The two planes ABC and ABC correspond toplanes through the minor axis a-a and the major axis bb of the nozzle asshown in FIG. 4. The angles a and a, for a system having an ellipticaldischarge orifice will be hereinafter referred to as the angles of majorconicity (a) and minor conicity (a") whereas the half angle a forsystems constituting frustums of right circular cones will be referredto simply as the conicity angle. In all cases the conicity angle is torange between 4 and 20 and preferably between 5 and 18. The ratiobetween the major half axis and the minor half axis of the ellipse iscomprised between 5 and 1 and preferably between 2.5 and 1.25. It isevident, ofcourse, that a ratio of 1 (1:1 corresponds to a rightcircular cone frustum.

The actual cross-sectional area of the discharge orifice, the dimensionsof the chamber 3 or 3 and the area of inlet orifice 5, 5' will beselected in accordance with the flow rate of thedibromotetrafluoroethane desired. The extinguishing compound is used atthe ambient temperature required for the extinction of the fire and maydepend upon the season and location of use. In general, temperaturesofl0 C. to +40 C. will prevail at the discharge orifice. While thedibromotetrafluoroethane may be sprayed under a pressure that will varyaccording to the requirements, e.g. as determined by the desired flowrate and nozzle temperature, it has been found that best results areobtained in terms of fire extinguishing action, with a pressure between4 and 20 atm. and preferably 6 and 16 atm.

As noted earlier, this pressure may be obtained by means of a mechanicaldevice, for example, a pump, or by a propellant which may be soluble orinsoluble in dibromotetrafiuoroethane. Suitable insoluble propellantsinclude nitrogen, helium, air or other pressurized inert gas, also theuse of air is possible only when the air lies above the body of theliquid in the container and the latter is driven to the nozzle via aduct leading below the compressed air. Partially soluble propellantgases, such as carbon dioxide may be used. As described in theaforementioned copending application, the propellant may even be solublein the dibromotetrafluoroethane and, for this purpose, halogenated andpreferably fluorinated and/or chlorofluorinated or bromofluorinatedmethanes are used. Best results are obtained withdifluorodichloromethane, difluoromonochloromethane,trifluorobromomethane and tetrafluoromethane individually or in mixturesof two or more; preference is, however, given to insoluble propellantsfor the purposes of the present invention.

The surprisingly high efficiency of the flame-quenching activity ofdibrometetrafluoroethane, used in accordance with the present invention,can be seen from the time required to extinguish a particular fire andthe consumption of this compound to completely quenching of the flame.It cannot be explained by any known theory, to our knowledge, but webelieve, without intending to be limited by this hypothesis that it is aconsequence of the fact that, with a nozzle constructed as described andat the indicated pressures, the

dibromotetrafluoroethane is not nebulized or atomized into particles inthe size range of microns as is the case with aerosol sprays, nor doesthe dibromotetrafluoroethane form excessively large particles. e.g.upwards of5 mm. It appears that the nozzle results in the formation of aparticle size between 0.5 and 3 mm. and that this particle size rangehas-the surprising effect of increasing the fire-extinguishingcapabilities of this particular compound. In extending these hypothesesfurther, we may visualize the nebulization or dispersion in a particlesize range of the order of microns to promote mechanical dispelling fromthe site of combustion and permitting rapid evaporation prior to entryof the particles into the combustion zone in which the particles mayfunction to absorb. Furthermore it appears that nebulization may induceair toward the combustion site and promote combustion at least to acertain extent. Particles of a larger size than those produced inaccordance with the present invention appear to pass through the flameand again remain out of the flame site so as to be incapable ofwithdrawing heat therefrom by evaporation.

ln FIG. 6 we show an installation wherein the nozzle N or N is mountedon a valve structure V connected by a hose H to a tank T containing theBrF C-CF Br and charged with a propellant gas at G. A gauge G indicatesthe pressure. When no propellant gas is employed, a pump P serves todrive the flameextinguishing substance.

EXAMPLE 1 A portable fire extinguisher of 6 l. holding capacity wasloaded with 6.5 kg. of symmetrical dibromotetrafluoroethane and was thenpressurized at room temperature (about C.) with nitrogen, theextinguisher being equipped to ensure the constant operating pressurerequired during the spraying of the extinguishing product (i.e. 8 atm.).

The extinguishing test was carried out in a 1.5 m? (flame area) tankcontaining about 100 liters of water and 20 liters of a gasoline/gas-oilmixture in a weight ratio of 1:1.

The extinguisher was introduced after 30 seconds of combustion (thistime will hereinafter be always indicated as precombustion time). Thefire was extinguished within a second with a consumption inextinguishing compound 0 about l kg.

The nozzle used with the fire extinguisher was of the type representedat FIG. 1 with an orifice of circular shape and a conicity 0r=8; theorifice area was of 16 mm EXAMPLE 2 Into the 100-liter tank of a wheeledextinguisher was charged 180 kg. of C F Br and it was then pressurizedas in Example 1.

The test was carried out in a 1.5 m. tank containing about 100 liters ofwater and 20 liters ofa gasoline/gas-oil mixture in a weight ratio of1:1. The extinguisher was introduced after a precombustion time of 30sec. and the fire was extinguished within 1 sec. with a consumption ofextinguishing compound of about 1 kg.

The nozzle used with the fire extinguisher was of the type representedin FIG. 3 having an orifice of elliptical shape and with a conicitya'=8, a"=6. the orifice flow cross section amounting to 20 mm. and theratio of the major half axis (d) to the minor halfaxis (d") was 3:2.

EXAMPLE 3' The same test as that of Example 2 was repeated following iEXAMPLE 4 The test of Example 3 was repeated following the sameprocedures and using the same equipment.

With a precombustion time of 60 seconds the extinguishing time amountedto 3 seconds with a consumption in extinguishing compound of 2.8 kg.

EXAMPLE 5 A portable fire extinguisher of 6-1iter capacity was loadedwith 6.5 kg. of C F Br and was then pressurized at room temperature(about 20 C.) with nitrogen to a pressure of. l 6 atm.

Thereupon three successive tests were carried out as follows: suring thespraying of the extinguishing product the pressure decreased, owing tothe discharge to a pressure of (a) 13 atm. at the end of the first test;(b) of 10 atm. at the end of the second test; and (c) of 7 atm. at theend of the third test. The extinguishing tests were carried out in atank of 1.5 m? combustion area containing about liters of water and 20liters of a gasoline/gas-oil mixture in a ratio of 1:1.

With a precombustion time of 30 see. the extinguishing time obtained wasbetween 1 and 2 sec. for each test. The total consumption ofextinguishing product amounted to 5 kg.

The nozzle used on the fire extinguisher was of the type represented inFIG. 3 and had an elliptical shaped orifice'and the conicity a=8 anda"=6; the orifice surface was 20 mm. while the major half axis; minorhalf axis ratio was equal to 3:2.

We also carried out extinguishing tests on fires from combustiblesubstances as for instance of hydrocarbons, alcohols,

ketones, carbon sulfide, etc. in the absence of water in the EXAMPLE 6The equipment used was the same as that described in Example 2 and thesame procedure was followed, carrying out the test in a 1.5 m?(combustion area) tank containing about 10 liters of carbon sulfide Witha precombustion time of 30 seconds the fire was extinguished in 1 sec.with a consumption of extinguishing compound of 0.5 kg. Furtherextinguishing tests were carried out whose results, for illustrativepurpose, are recorded in the Tables on the following page.

"iiif e Tables: n I I Time of precombustion time interval between thebeginning of the fire and the use of the extinguisher;

A gasoline/gas-oil mixture (ratio by weight 2:1) 40 liters of mixture ona base of water;

A gasoline/gas-oil mixture (ratio by weight 1:1) 20 liters of mixture ona base of water;

A, gasoline/gas-oil mixture (ratio by weight 1:1) 60 liters of mixtureon a base of water;

A, 'gasoline/gas-oil mixture (ratio by weight 1:1) 50 liters of mixtureon a base of water;

A transformer oil, 10 liters:

A gasoline/gas-oil mixture (ratio by weight 1:1) 230 liters of mixtureon a base of water;

A gasoline/gas-oil mixture (ratio by weight l-l) 350 liters of mixtureon a base of water;

A,, gasoline/gas-oil mixture (ratio by weight 1:1) 400 liters of mixtureon a base of water;

A gasoline/gas-oil mixture (ratio by weight 2:1) 900 liters of mixtureon a base of water;

A gasoline/gas-oil mixture (ratio by weight 2:1) 600 liters of mixtureon a base of water.

All the tests reported on Tables 1 and 3 were carried out by oneoperator who was at a distance of about 3 meters from the fire tank;

The tests reported on Table. 2 were carried out by one operator (withthe exception of tests Nos. 5, 6, 7, 8 and 9 which were carried out bytwo operators) who was at a distance greater than 3 meters from the firetank (from about 3 to 5 meters).

The test No. I (Table 2) was carried out in a fire tank of 6 m.'-'(combustion area) provided with a dividing wall located in the middleofthe tank.

The test No. 5 (Table 2 l was carried out by two operators.

The test No. 6 (Table 2) was carried out by two operators on afire areaof 50 m? constituted of a deck house (engine room ofa ship) with all itsstructures (pipes. grates, etc.

The tests Nos. 7. 8 and 9 (Table 2) were carried out by two operators ina fire tank having St. Andrea's cross shape (X- shape). the arms of thecross being 10 m. X 4 m.; test No. 10 was carried out on the same tankby one operator.

From the preceding Examples and Tables it willbe clearly seen howsurprisingly high the efficacy of the extinguishing activity is when thenozzle according to this invention is used.

The advantages of this invention will be evident when it is understoodthat with the process of the present invention fires of considerableextent (of the order of several tens of m?) may be quenched in a veryshort time (of the order of a few seconds). with low consumption ofextinguishing product (as low as the order of 0.5 kgJmF) andfrom adistance more than sufficient to ensure the safety of the personnelcharged with the fire-extinguishing activity (of the order of from 3 to5 meters). It was also found that for fire areas of large dimensions theelliptical shape of the nozzles orifice is more efficient than thecircular shape. 1

The method of this invention extinguishes various kinds of firesincluding those whose combustible material is a solid (such as paper,wood, fabrics, plastic materials, etc.) those caused by a liquid, a fator ofelectrical origin and so forth.

We claim:

1. A method of extinguishing fires and quenching flames comprising thestep of directing symmetricaldibromotetrafluoroethane thereagainstthrough a nozzle having a discharge orifice trained on a fire and itsflame; and conducting said dibromotetrafluoroethane to said orificethrough a chamber of substantially forced conical configurationconverging toward and terminating at said orifice while having aconicity angle between about 4 and about 20.

2. The method defined in claim 1 wherein said chamber has a conicityangle ofsubstantially 5 to 18.

3. The method defined in claim 1 wherein said orifice is of circularconfiguration and said chamber has the configuration ofa frustum ofaright circular cone.

4. The method defined in claim 1 wherein said discharge orifice is ofelliptical configuration, said chamber having an inlet orifice ofcircular configuration spaced from said outlet orifice and forming asmooth transition between the circular inlet orifice and the ellipticaldischarge orifice.

5. The method defined in claim 4 wherein said discharge orifice has amajor half axis and a minor half axis in a ratio of substantially 5:l tolzl.

6. The method defined in claim 5 wherein said ratio ranges between 25:1to L251].

7. The method defined in claim 5 wherein said chamber has an angle ofmajor conicity and an angle of minor conicity different from one anotherand each ranging between 4 and 20.

8. The method defined in claim 1 wherein the dibromotetrafluoroethane isforced through said chamber at a pressure of substantially 4 to 20 atm.

9. The method defined in claim 8 wherein said pressure is 6 to l6 atm.

10. The method defined in claim 1, further comprising the step ofdriving said dibromotetrafluoroethane through said chamber with apropellant insoluble in said dibromotetrafluoroethane and selected fromthe group which consists of nitrogen helium, another inert gas and airunder pressure.

11. The method defined in claim 1 further comprising the step ofdisplacing sald said dibromotetrafluoroethane through said chamber witha propellant partially soluble in the dibromotetrafluoroethane.

12. The method defined in claim 11 wherein said propellant is carbondioxide.

13. The method defined in claim 1 wherein said dibromotetrafluoroethaneis driven through said chamber in said with at least one propellantsoluble dibromotetrafluoroethane and selected from the glroup conststingof fluormated, chlorofluormated and bromo uorinated methanes.

14. An apparatus for quenching flames and extinguishing fires comprisinga reservoir if dibromotetrafluoroethane and a nozzle for dispensingdibromotetrafluoroethane connected to said reservoir, said nozzle havinga nozzle body formed with a discharge orifice and a chamber leading tosaid discharge orifice and frustoconically converging in the directionthereof with a conicity angle of about 4 to about 20.

15. The apparatus defined in claim 14 wherein said discharge orifice isof circular configuration and said chamber has the configuration of afrustum of a right circular cone.

16. The apparatus defined in claim 14 wherein said discharge orifice isof elliptical configuration with a ratio of its major halfaxis to itsminor halfaxis between 5:1 and 1:1.

17. The apparatus defined in claim 14, further comprising pump means fordisplacing said dibromotetrafluoroethane through said nozzle.

2. The method defined in claim 1 wherein said chamber has a conicityangle of substantially 5* to 18*.
 3. The method defined in claim 1wherein said orifice is of circular configuration and said chamber hasthe configuration of a frustum of a right circular cone.
 4. The methoddefined in claim 1 wherein said discharge orifice is of ellipticalconfiguration, said chamber having an inlet orifice of circularconfiguration spaced from said outlet orifice and forming a smoothtransition between the circular inlet orifice and the ellipticaldischarge orifice.
 5. The method defined in claim 4 wherein saiddischarge orifice has a major half axis and a minor half axis in a ratioof substantially 5:1 to 1:1.
 6. The method defined in claim 5 whereinsaid ratio ranges between 2.5:1 to 1.25:1.
 7. The method defined inclaim 5 wherein said chamber has an angle of major conicity and an angleof minor conicity different from one another and each ranging between 4*and 20*.
 8. The method defined in claim 1 wherein thedibromotetrafluoroethane is forced through said chamber at a pressure ofsubstantially 4 to 20 atm.
 9. The method defined in claim 8 wherein saidpressure is 6 to 16 atm.
 10. The method defined in claim 1, furthercomprising the step of driving said dibromotetrafluoroethane throughsaid chamber with a propellant insoluble in saiddibromotetrafluoroethane and selected from the group which consists ofnitrogen helium, another inert gas and air under pressure.
 11. Themethod defined in claim 1 further comprising the step of displacing saIdsaid dibromotetrafluoroethane through said chamber with a propellantpartially soluble in the dibromotetrafluoroethane.
 12. The methoddefined in claim 11 wherein said propellant is carbon dioxide.
 13. Themethod defined in claim 1 wherein said dibromotetrafluoroethane isdriven through said chamber with at least one propellant soluble in saiddibromotetrafluoroethane and selected from the group consisting offluorinated, chlorofluorinated and bromofluorinated methanes.
 14. Anapparatus for quenching flames and extinguishing fires comprising areservoir if dibromotetrafluoroethane and a nozzle for dispensingdibromotetrafluoroethane connected to said reservoir, said nozzle havinga nozzle body formed with a discharge orifice and a chamber leading tosaid discharge orifice and frustoconically converging in the directionthereof with a conicity angle of about 4* to about 20*.
 15. Theapparatus defined in claim 14 wherein said discharge orifice is ofcircular Configuration and said chamber has the configuration of afrustum of a right circular cone.
 16. The apparatus defined in claim 14wherein said discharge orifice is of elliptical configuration with aratio of its major half axis to its minor half axis between 5:1 and 1:1.17. The apparatus defined in claim 14, further comprising pump means fordisplacing said dibromotetrafluoroethane through said nozzle.